Improving safety margins of the petzl adjust through improved rope choice

We all know nobody likes the original rope in the petzl adjust, ironically, it's quite difficult to adjust even when not weighted. As such many choose to replace it with accessory cord or half ropes. This replacement of cord comes I feel as a bit of unknown as after all we don't have a great idea how the adjust fails, we just assume it will slip. 

This is the result my friend had from a fall test using an old gen edelrid rap line with the adjust, this was read to happen at just 3.4kn. What's happened here?

 I'd guess the rap line has a weak sheath and most of the strength is found in the core causing quick failure of the sheath. If this is the case any cord or rope with a weak sheath may have a similar failure mod. Accessory cords have no listed sheath percentage, halfs and twins generally have a pretty low sheath percentage. 

So, solving this problem, does anyone know of any cords or ropes that might be particularly suitable to avoid this failure mode? I'm thinking super strong sheaths, maybe dyneema if it can be made to not slip. If anyone has any large diameter dyneema cord I'd be interested to see if that works. 

Yes 6mm accessory cord can work even taking high FF daisy falls, but, it would be foolish to say cord is cord and it would be better to find a single product optimised for this use. 

Does Unicorn not solve this since it bonds or sews the sheath to the core? Or is Unicorn tech only used on halves and twins not thinner than about 7mm and you're looking for thinner?

Jake woo wrote:

Does Unicorn not solve this since it bonds or sews the sheath to the core? Or is Unicorn tech only used on halves and twins not thinner than about 7mm and you're looking for thinner?

Unicore is trash, it's a weak glue and does nothing to actually improve the durability or cut resistance of the sheath. It marginally improves the cut resistance of the rope by preventing the sheath from slipping down and revealing the fragile core strands in the event of a sheath having a significant portion of it's yarns severed. I'd rather the sheath of my rope not fail catastrophically in the first place and as such, I think edelrid are ahead in the cut resistant rope game. But I digress. 

Thickness doesn't matter provided it operates smoothly in the adjust. 

Just realised I posted in the wrong forum, this will be locked and moved.